How to Cultivate and Manage Pomelo for Good Growth

1. Planting: Pomelo trees like warmth and moisture, and need fertilizer and water. They require deep, fertile soil. Special attention must be paid to planting pomelo trees in soil that is relatively fertile and has sufficient moisture, or in places with good water source conditions. 1. Planting time. Generally, spring and autumn rainy seasons are suitable. Spring from late February to late April; autumn from mid-September to mid-October. If conditions permit, planting can also be done in other seasons, but it is not suitable to plant under conditions of low winter temperatures and summer drought. 2. Planting density. Plant spacing of 4x4 m or 4x5 m, generally about 40 trees per mu, or dwarfed and close planting with 50-60 trees per mu. 3. Planting method. (1) Before planting, dig a large pit 1 m square, apply a large amount of organic fertilizer and an appropriate amount of phosphate fertilizer as base fertilizer, and backfill soil to 20-30 cm above the ground. (2) When planting, gently place the seedling in the hole, plant with loose crumbled soil, press the fine soil around the root ball firmly with your hands, and expose the graft union above the ground. (3) After planting, make the planting basin 20 cm above the ground and water thoroughly to settle the roots.

2. Soil cultivation: 1. Deep plowing and hole expansion to mature the soil. Deep plowing to improve the soil and mature the soil must start from the establishment of the orchard and expand year by year. For young trees, ring-shaped trenches can be dug around the planting area and deep plowed year by year. In mature pomelo orchards, strip trenches can be dug outside the canopy, about 0.5-0.7 m deep and wide, with green manure and other organic and inorganic fertilizers buried in layers. Deep plowing can also be done every other year, every other row, or by rotating positions for each tree each year. 2. Plant green manure extensively. Use the land and nourish the land. Planting green manure extensively to cover the ground can prevent erosion in summer, lower soil temperature, increase air humidity and suppress weeds, while also increasing soil organic matter and improving soil fertility. If interplanting legumes, vegetables, etc., it can also increase early returns; their stalks and residual branches and leaves can be used as cover and turned into the soil to increase soil organic matter. 3. Intertillage and earthing up. Intertillage should be combined with weeding, generally 3-4 times a year, that is, after fruit harvest in winter, in summer or autumn, and once each in combination with sowing and intercropping. The depth of intertillage is 10-15 cm (appropriately deeper when combined with intercropping and sowing), and the closer to the trunk, the shallower it should be to avoid damaging large roots. Earthing up should be done before the dry season arrives or after fruit harvest in winter. In gently sloping areas, earth up once every 3-4 years; in places with steep slopes and severe erosion, earth up once every other year.

3. Fertilization. Young trees are small and their roots are young and tender, so it is advisable to apply fertilizer frequently and lightly, 5-6 times a year. For fruiting trees, generally 4 applications are needed, namely recovery fertilizer, bud-promoting fertilizer, fruit-stabilizing fertilizer and fruit-sizing fertilizer. 1. Recovery fertilizer (base fertilizer): Apply before and after fruit harvest. Its application amount accounts for half of the annual fertilization amount. A large amount of slow-release fertilizers such as green manure, compost, barnyard manure and cake fertilizer should be applied, together with quick-acting nitrogen fertilizer and phosphate fertilizer. 2. Bud-promoting fertilizer (pre-flowering fertilizer): Generally carried out in February-March. This fertilizer should be mainly quick-acting nitrogen fertilizer, mainly applying human and livestock manure, with appropriate addition of urea. 3. Fruit-stabilizing fertilizer: Apply quick-acting nitrogen fertilizer and phosphate fertilizer half a month before the June fruit drop. Rotten human and livestock manure can be applied, and 1% superphosphate extract can be sprayed. 4. Fruit-sizing fertilizer: Apply in mid-to-late June, applying quick-acting nitrogen fertilizer and phosphate-potassium fertilizer.

4. Irrigation and drainage. Pomelo trees are evergreen all year round, have a large annual shoot growth, a long fruiting period, large leaves and large fruits, and have high water requirements. When cultivating pomelo trees, irrigation must be used to ensure their water requirements. Irrigation should be based on the water needs of pomelo trees at each phenological stage and the drought conditions at the time. Overall, the entire annual growth and development process requires an appropriate amount of water, especially during spring bud germination and flowering, and during the peak fruit growth period, when they are most sensitive. When there is spring drought or summer drought, irrigation must be carried out. In low-lying areas, places with high groundwater levels, or during the rainy season, attention should be paid to drainage. Before the rainy season arrives or during heavy rain seasons, the drainage system of the pomelo orchard should be checked at any time, repaired and dredged promptly, so that drainage is smooth and unobstructed.

5. Training and pruning. Pomelo trees have strong vigor and a tall body. In the young stage, under sufficient fertilizer and water conditions, apical dominance is strong, shoots grow upright, and a tree shape with an obvious trunk is easily formed. New shoots are numerous and vigorous. After fruiting, branches droop due to the weight of the fruit, and branches bend downward, causing the tree shape to become umbrella-like. Light cannot easily penetrate into the interior of the canopy, so branches weaken and fruits become small. Most of the fruiting mother branches of pomelo trees are inside the canopy, and are biennial leafless branches (commonly known as claws). According to the growth and fruiting characteristics of pomelo trees, in production it is advisable to choose the “modified central leader form” and the natural “open-center form”. The trunk height should be 40-60 cm, with 30-40 cm between main branches, and a total of 5-6 main branches should be trained. When pruning pomelo trees, the principle should be “heavy at the top, light on all sides, heavy on the outside, light on the inside”, that is, where branches and leaves are dense around the canopy, prune to thin them out; heavily prune the top branches and lightly prune the internal branches, so that the interior of the canopy has good light, and the fruit is abundant and of good quality. Generally, the relatively slender leafless branches on 3-4-year-old lateral branches inside the canopy are excellent fruiting mother branches and must be retained. For lateral branches outside the canopy that are too long or disturb the tree shape and affect balanced tree vigor, attention should be paid to thinning and heading back, so as to achieve the goal of ventilation and light penetration.

6. Pest and disease control. There are many pests and diseases harmful to pomelo trees. Common ones include mites, scale insects, leafminers, anthracnose, etc. Control should be based on the occurrence characteristics of each disease and combined with spraying. 1. From late February before flowering to early April, spray continuously 2 times, mainly to control mites, while also controlling other pests. Use pesticides: insecticide + acaricide + fungicide. 2. In the young fruit stage after flower drop, from mid-May to late June, spray continuously 2 times, mainly to control scale insects, while also controlling other pests. Use pesticides: insecticide + fungicide. 3. In autumn, from mid-July to early September, spray continuously 3-4 times, mainly to control leafminers, and also to control swallowtail butterflies, anthracnose, etc. Use pesticides: insecticide + fungicide. 4. From mid-September to early October is the second peak of mite damage. Spray 1-2 times to kill mites, while also controlling other pests and diseases. Use pesticides: insecticide + acaricide + fungicide. 5. In winter, spray once with lime sulfur mixture to clean the orchard.

For insecticides, chlorpyrifos, trichlorfon, fenpropathrin, Dagongchen, etc. can be selected and used alternately. For fungicides, any one of carbendazim, thiophanate-methyl, zineb, etc. can be selected. For acaricides, propargite, mie man ling, etc. can be selected and sprayed alternately. Spraying should be uniform and thorough.

High-quality and high-yield cultivation and management techniques for pomelo

1. Strengthen shoots and promote shoots to turn green. For vigorous trees, when spring shoots are 4-7 cm, spray 15%, 600 times paclobutrazol, to make spring shoots short and strong and inflorescences robust. During the leaf expansion stage of spring shoots, spray the canopy with Lüfenwei to promote leaves to turn green. 2. Plastic film mulching to retain moisture and regulate temperature. In summer and autumn, temperatures are high and soil moisture evaporation is large. In the orchard, use plastic film mulching between rows or interplant low-growing vegetables, peanuts, and leguminous crops as cover. In summer, high temperature and summer drought can retain moisture, suppress weed overgrowth, help pomelo trees grow and develop, increase pomelo yield, and increase the economic benefits of the pomelo orchard. 3. Timely pollination to increase fruit set. (1) For artificial pollination, choose clear and good weather, collect fully opened male flowers of pomelo trees, wrap the pollen in white paper, put it into a cloth bag, tie it around a person's waist and wrap it around the body once. After 24 hours, take out the pollen, add 0.1% borax and mix, then use a brush or cotton swab to apply it to the stigma of pomelo flowers. (2) For insect pollination, mix 0.2% urea plus 0.3% granulated sugar plus 1.2% bee sugar plus 98% clear water, and spray the stigma of pomelo flowers with a miniature sprayer on sunny days from 8-10 am and 3-4 pm, continuously spraying 2-3 times, to attract bees for pollination and increase fruit set. 4. Timely fruit thinning. When young fruits grow to the size of peas, carry out the first fruit thinning, mainly removing small fruits, diseased and insect-damaged fruits, and deformed fruits. Generally, according to 1-1.5 times the tree's bearing capacity, when the fruit grows to the size of a thumb, carry out the second fruit thinning. At this time, the retained fruits should be uniform in size and evenly distributed. 5. Young fruit transplanting. When pomelo fruits grow to the size of eggs, cut off overly dense young fruits or twin fruits and transplant them to branch sequences with fewer fruits, so that nutrient supply is sufficient, fruits become larger, and yield increases. 6. Flower and fruit retention. During the flower bud stage, spray the canopy with 0.1% Lüfenwei foliar fertilizer plus 0.1% borax, plus 0.2% ammonium molybdate plus 0.2% potassium dihydrogen phosphate plus 0.3% urea, mixed and sprayed on the canopy 2 times (once every 7 days). When three-quarters of the flowers have faded, use 1 bag of fangluosu plus gibberellin 20x10-6, first dissolved with alcohol, then spray the canopy. During the physiological fruit drop period, use cytokinin (ba) 1 g dissolved in alcohol and diluted with water to 200x10-6, apply once to the fruit stalk from mid-April to early May, and apply again to the fruit stalk from late May to mid-June. 7. Do a good job in disease control. (1) To control flower bud maggots, during the peak emergence period of adult eclosion after rain, use 3% carbofuran granules 0.8 kg per mu mixed with 25 kg river sand and broadcast on the ground. Use 90% trichlorfon (or 80% dichlorvos emulsion) 600 times to spray the canopy 1-2 times. Manually remove damaged flower buds in time, blanch them with boiling water, and bury them deeply. (2) To control arrowhead scale and cottony cushion scale, spray xichai mixture 1-2 times during the peak hatching period of the first-generation young scales in early to mid-May. The xichai mixture (washing powder 0.5 part + diesel 1 part) is prepared as an 80-100 times solution, or 40% supusha emulsion 1500-2000 times solution can be used alternately. (3) To control red and yellow spiders. Use 5% hexythiazox 2000 times plus 40% isocarbophos 800 times solution, or propargite 2000 times solution mixed with a small amount of diesel and spray the canopy 1-2 times. (4) Winter trunk coating. Use quicklime 6 kg, plus lime sulfur mixture stock solution 1 kg, plus salt 1 kg, plus omethoate 50 g, add water 15 kg, and coat the main trunk of pomelo trees to control pests and diseases. 8. Strengthen fertilizer and water management. During the young tree tending period, vegetative growth is dominant, and a canopy that bears early and abundantly should be cultivated. Therefore, each year before and after spring, summer, and autumn, apply 1 shoot-promoting fertilizer and 1 shoot-strengthening fertilizer each, applying 5-8 kg farmyard manure plus 0.1-0.2 kg urea per tree as a mixed application. After entering the fruiting stage, generally apply spring fertilizer lightly in early February, applying 50 kg farmyard manure plus 0.3-0.4 kg urea per tree. In mid-May, apply fruit-stabilizing fertilizer appropriately, applying 0.1% Lüfenwei foliar fertilizer 1-2 times per tree, or 0.2% potassium dihydrogen phosphate and 0.3% urea mixed for root-outside topdressing. In mid-July, apply fruit-sizing and shoot-promoting fertilizer heavily, applying 60 kg farmyard manure powder plus 1 kg superphosphate and 2 kg plant ash per tree as a mixed application. In mid-to-late September, apply post-harvest escort fertilizer deeply (also called rejuvenation fertilizer), applying 60 kg farmyard manure plus 1 kg oil cake per tree as a mixed application, to restore tree vigor. 9. Do a good job in training and pruning. (1) Pinch promptly. For spring and summer shoots, when they grow to about 30 cm, pinch them promptly and remove excess buds. (2) Prune and train the tree shape. In autumn, for strong and vigorous trees, take measures such as propping, pulling, and hanging to increase the opening angle, ease growth vigor, and promote early fruiting. (3) Ring cutting to promote flowering. In late September, use a sharp knife to make 3 staggered ring cuts on lateral branches, preventing nutrients produced by leaves from being transported downward, increasing the accumulation of organic nutrients in leaves, and effectively increasing the number of flowers the following year. (4) Control late autumn shoots and winter shoots. Late autumn shoots and winter shoots issued after early November will consume a large amount of nutrients and are not conducive to flower bud differentiation of fruiting mother branches the following year. After autumn shoot leaves turn green and mature, spray 300 times paclobutrazol inhibitor 1-2 times, which can effectively avoid the emergence of winter shoots. (5) Pruning and thinning branches. After fruit harvest, remove 1-2 vigorous large branches in the middle and upper part of the canopy to enhance light penetration into the inner canopy. In pruning, the principles of heavy at the top and light at the bottom, heavy outside and light inside should be grasped. There should be more thinning and less heading back, with timely and moderate pruning. Cut off overlapping branches, crossing branches, diseased and insect-damaged branches, competitive branches, dead branches and fruit stalks. For clustered branches, thin three to leave one, and thin five to leave two, so that shoots are evenly distributed. Retain as much as possible the lateral branches inside the canopy, short fruit branches, lower leafless branches, and drooping branches, so that the canopy is ventilated and light-transmitting, achieving continuous high and stable yields. 10. Timely harvest. Generally, harvesting in late November is suitable. Choose sunny days for harvesting. During harvesting, transportation and storage, handle gently. For storage and fresh-keeping, use 2,4-d plus carbendazim solution to wash the fruit for sterilization, then pack and store each fruit individually in fresh-keeping bags.

Scientific fertilization of pomelo: 1. Fertilization of 1-3-year-old young trees. To strengthen the growth of young trees and achieve early high yield, fertilization should be carried out multiple times in accordance with the characteristic of pomelo trees sending out shoots multiple times. Fertilizing before shoot emergence can promote shoot emergence and make shoots grow robustly. Topdressing should be mainly quick-acting fertilizer. Fertilization method: apply frequently and lightly, with more spring shoot fertilizer. Fertilization times are February, May, and July respectively. If it is desired to start fruiting in the second year after planting, then during the autumn shoot filling period, appropriately increase phosphate and potassium fertilizer and reduce the amount of nitrogen fertilizer. To promote flowering, during the flower bud differentiation period (December), spray strong trees with 0.3-0.6% potassium dihydrogen phosphate 2-3 times; spray weak trees with 0.2% potassium dihydrogen phosphate plus 0.4-0.5% urea 3-4 times. A large amount of organic fertilizer, green manure, and phosphate and potassium fertilizer should also be supplemented, and the upper soil layer should be prepared well to promote good horizontal root development, so as to facilitate early fruiting and high yield. 2. Fertilization of fruiting trees. Fertilization of fruiting trees is generally divided into four applications, namely recovery fertilizer, shoot-promoting fertilizer, fruit-stabilizing fertilizer and fruit-sizing fertilizer. 1. Recovery fertilizer (base fertilizer). Fertilization time: before and after fruit harvest; important role of fertilization: because pomelo trees bloom and fruit and consume a large amount of nutrients, in order to restore tree vigor, promote flower bud differentiation, enrich fruiting mother branches, and ensure nutrient needs for the following year, sufficient base fertilizer must be applied. Fertilization amount generally accounts for 50% of the annual fertilization amount; types of fertilizer: slow-release fertilizers such as green manure, compost, cake fertilizer, together with quick-acting fertilizer and phosphate fertilizer (superphosphate is best). Fertilization method: dig ring-shaped trenches outside the canopy; phosphate fertilizer below, urea above. 2. Bud-promoting fertilizer (flower bud fertilizer). Fertilization time: February-March; important role of fertilization: it can promote spring shoot emergence, supply the needs of flowering and fruiting, and lay a good foundation for the current year's shoot emergence and fruiting and for strong fruiting mother branches the following year; it can overcome alternate bearing and achieve high and stable yields. Therefore, fertilization is an important measure to increase yield; types of fertilizer: quick-acting nitrogen fertilizer should be dominant, such as human manure and urine or urea, ammonium sulfate, etc. 3. Fruit-stabilizing fertilizer. Fertilization time: half a month before the second physiological fruit drop (June); important role of fertilization: to compensate for the nutrients consumed by flowering and the nutrients needed by young fruits, reduce fruit drop, increase fruit set rate, and ensure high yield; types of fertilizer: quick-acting nitrogen fertilizer and phosphate fertilizer, and human manure and urine can also be applied, and 1% superphosphate extract can be sprayed. 4. Fruit-sizing fertilizer. Fertilization time: before autumn shoots, carried out in May-June; important role of fertilization: in July-August, fruits grow rapidly and at the same time a large number of autumn shoots are sent out, creating a contradiction in competing for nutrients and water; types of fertilizer: in order to accelerate fruit growth, improve fruit quality, and at the same time promote the occurrence of autumn shoots, quick-acting nitrogen fertilizer and phosphate-potassium fertilizer need to be topdressed. For adult fruiting trees, generally apply base fertilizer; in February apply 150 kg human and livestock manure per tree, while adding oil cake; in May apply 100 kg human and livestock manure per tree; in July apply 150 kg human and livestock manure per tree, adding an appropriate amount of superphosphate.

Training and pruning of pomelo trees: Through training and pruning, pomelo trees are made to have a full canopy shape and achieve the goal of high and stable yield. 1. Trunk determination. The trunk height should be 40-60 cm, and a total of 5-6 main branches should be trained. The biological characteristics of pomelo trees are different from other sweet oranges and red tangerines. They have strong vigor, a tall body, and are too large, and most or all of their fruiting mother branches are distributed inside the canopy. We must understand these characteristics in order to master pruning techniques. 2. Fruiting mother branches. Shoots that send out fruiting branches are called fruiting mother branches. Fruiting mother branches can be roughly divided into three types: 1. Small lateral branches borne on large lateral branches. This kind of branch grows weakly and cannot extend out of the canopy as a vegetative branch. After continuous growth for 2-3 years, it produces leafless fruiting mother branches and sends out shoots to fruit. 2. Leafless branches. The nutritional conditions for flowering and budding of this kind of branch are insufficient, and generally they flower and fruit only by the third year. 3. Flower-drop and fruit-drop branches (commonly known as blind-eye branches). They have no germinated buds and will flower and fruit the following year. 3. Fruiting branches. They are formed by the germination of one bud at the top of the fruiting mother branch or several nearby buds. Fruiting branches are divided into leafy fruiting branches, branches with both flowers and leaves, and leafless fruiting branches. There may be one flower to many flowers, and fruiting branches with no inflorescence and few-leaf inflorescences are the best. 4. Purpose and significance of pruning. The interior of the canopy is well ventilated and light-transmitting, the fruiting mother branches in the inner canopy are nutritionally rich, and the fruit is abundant and of good quality. 5. Pruning principles. Achieve emptiness outside but not inside, heavy pruning at the top, light pruning on all sides, heavy pruning outside, light pruning inside. 6. Pruning methods. Pay attention to retaining the relatively weak leafless branches on lateral branches inside the canopy; these are excellent fruiting mother branches. Those with vigorous vegetative growth and overly dense branches and leaves should be heavily pruned; those with weaker vegetative growth should be lightly pruned. 7. Pruning time and branches that should be cut off. After fruit harvest, cut off the vertical upright and drooping branches inside the canopy, and remove dead branches, diseased and insect-damaged branches, shaded branches, and heavily overlapping crossing branches. Summer pruning: in summer, remove some overly dense and overly vigorous new shoots, thin out overly dense weak branches, and head back vigorous water sprouts.

Promoting flowering and retaining fruit in pomelo. 1. Promoting flowering. To make fruit trees bloom early, in the year before fruiting, the vegetative growth of the tree must be controlled, the growth center must be shifted to reproductive growth, and flower bud differentiation must be promoted: 1. Control the excessive growth of vertical roots, cultivate large growth of lateral roots and parallel roots, and promote flower bud differentiation. 2. Use propping, pulling, and hanging on branches to increase the angle between branches and trunk, weaken vegetative growth, and promote flower bud differentiation. 3. For vigorously growing young trees, in September-October carry out 1-2 rings of ring cutting on lateral branches. 4. In autumn, pay attention to drainage and water control, and cut off part of the root system to cause physiological drought in the plant, so as to promote flower bud differentiation. 2. Fruit retention. 1. Increase tree nutrients, strengthen fertilizer and water management, retain leaves as much as possible, and prevent abnormal leaf drop. 2. Control flower quantity and thin out deformed flowers and overly dense flowers. 3. Regulate spring shoots and remove summer shoots. If too many spring shoots emerge, excessive nutrient consumption will aggravate fruit drop, so spring shoots should be regulated after flower buds appear. Mainly remove the strong and vigorous spring shoots (vegetative branches) in the upper part of the canopy, flower branches with more than 5 leaves, and late spring shoots; when summer shoots sprout new buds, remove the tender shoots multiple times until after fruit set is determined in mid-July, then allow shoots to grow. 4. Control pests and diseases well. Common pests and diseases include red and yellow spiders, leaf-rolling moths, and resin disease, etc. 5. Spray plant hormones, such as cytokinin, Zhibaosu, Jinyunda-120, etc.

Pest and disease control of pomelo. 1. Foot rot (rotten crown scar). Damage symptoms: mainly damages the root neck of the main trunk. The bark at the base of the trunk of affected plants rots, causing yellow leaves and dead branches, weakened tree vigor, and reduced yield. In severe cases, the whole plant dies. The incidence is high in the high-temperature and rainy season from July to August. Control methods: 1. Scrape off the diseased tissue part and burn it centrally. After scraping, apply fungicide and protective agent. 2. Commonly used medicines include: apply 20-40 ppm 2,4-d and then apply thiophanate-methyl 100-200 times solution; Bordeaux mixture paste, that is, a mixture of copper sulfate 1 jin, quicklime 3 jin, and water 15 jin; in the early stage of disease or before disease occurrence, spray with Yunsheng 900-1100 times solution for control. 2. Gummosis. Damage symptoms: damages the main trunk and main branches, affects tree vigor, and in severe cases, the lesions expand and “ring-cut” the trunk, causing branches and trunk of the plant to die. Control methods: first scrape off the rough bark of the diseased part (until bluish-yellow is appropriate), then make several longitudinal cuts deep to the xylem, and then treat with 80 times duoxiaomei solution or 50% thiophanate-methyl or carbendazim 100-200 times solution. 3. Red and yellow spiders. Red spiders mainly damage leaves. Severely affected leaves lose their luster and become grayish white, causing leaf drop and dead shoots. Yellow spider damage causes leaves to deform and twist, causing leaf drop and dead shoots. The peak damage period is generally from mid-April to mid-to-early June; September is the second peak damage period. Control methods: 1. Clean the orchard in winter and spray 2-3 degrees Baumé lime sulfur mixture. 2. For chemicals, use Pingman 1500 times solution to spray and protect buds at the beginning of spring and summer shoot emergence, or spray for control when pest populations occur. 4. Cottony cushion scale, red wax scale, arrowhead scale. Damage symptoms: adults and larvae damage branches, leaves, and fruits, and cause sooty mold. Affected trees have weak growth, dead branches, and in severe cases death. Control methods: The key to scale insect control is to grasp the larval stage and concentrate spraying before adults form wax shells. Late March to late September is the peak period of scale insect damage, especially late April to mid-May, which is the key control period. Use Chujin 1000 times solution for spray control. 5. Leaf-rolling moth. Damage symptoms: larvae damage tender leaves, young fruits, and flower buds. The larvae often spin silk to bind young fruits and tender leaves together, bore into the fruit to feed, causing young fruits to turn yellow and drop. Control methods: 1. Clean the orchard in winter and remove overwintering larvae. 2. Chemical control, focusing after flower drop and when larval population density is high, using chemicals 1-2 times. 3. Pesticide selection: decamethrin emulsifiable concentrate 5000 times solution; 50% dichlorvos 800-1000 times solution; decamethrin 800-1000 times solution; Jinsheng 1500 times solution.

Preparation and use of lime sulfur mixture: The control targets of lime sulfur mixture are powdery mildew, rust, rot, brown spot, as well as red spiders, scale insects, etc. Its raw material ratio is quicklime:sulfur:water=1:2:10 (weight ratio). The preparation method is to weigh 1 part quicklime and pour it into already boiling water to boil, then remove the lime residue. Then slowly pour 2 parts sulfur powder, previously adjusted into a paste with a small amount of water, into the pot, stirring while pouring, and continue boiling for 45 minutes to one hour. When the liquid turns reddish brown and the residue is yellow-green, stop the fire. After filtering out the residue, it is the lime sulfur mixture stock solution. The method of use is that in winter, spray a 4-5 degrees Baumé diluted solution; in the growing season, use a 0.2-0.3 degrees Baumé diluted solution. When using, if 0.3-0.5% washing powder is added, the control effect is better. Water dilution multiple = (stock solution concentration minus use concentration) divided by use concentration = kg of water to be added.